Silver exchange traded funds were up nearly 3% Thursday morning after Moody’s said it has placed its triple-A rating on U.S. government bonds under review for possible downgrade.

Silver futures hit a fresh two-month high and traded over $39 an ounce on Thursday.

“The price of silver gave the best performance of precious metals [Wednesday] and leapt 6.3% at the peak,” broker Commerzbank said, according to a FastMarkets report. “This rise in price is likely to be due primarily to inflows to silver ETFs.”

The world’s largest silver ETF, iShares Silver Trust (NYSEArca: SLV), reported the biggest rise in its holdings since early May at 133 metric tons, the report said. Overall, the ETF holds more than 9,600 metric tons of silver, according to sponsor BlackRock.

The gold/silver ratio has fallen to its lowest in over a month, according to FastMarkets.